The present invention is concerned with a method and apparatus for repairing a vehicle such as an automobile which is lifted off the ground for service. It is especially directed toward a method and apparatus for repairing and replacing parts of the suspension systems using MacPherson struts.
When certain work needs to be done on a vehicle such as changing shock absorbers or springs, a common practice is to use a hydraulics lift to raise the automobile to above head height of the mechanic. A widely used jack or lift is one that has a large central hydraulically operated shaft which is extendable from the floor level to a height of six or seven feet or more. Adjustable arms are pivotally attached to the hydraulic lift so that after a car has been driven over the hydraulic shaft the arm can be extended outwardly so that they will be under the frame of the car. Then the hydraulic means is actuated and the car is lifted to the desired height.
When this occurs, it is apparent that the wheels are not directly supported by the hydraulic shaft or the arms but are supported by the suspension system. The tires are hanging down from their normal position in relation to the upper portion of the car and is held there only by the suspension system which is under tension and not in compression which is the normal state. The suspension system includes shock absorbers, springs and recently in most cars now being manufactured, the MacPherson struts. In the MacPherson strut, a strut assembly is mounted between the steering knuckle of a wheel and a strut bearing plate supported from the frame or body of the automobile. The strut assembly has a strut plate mounted therein. A coil spring is mounted around the strut assembly and is positioned under compression between the strut plate at the bottom and the strut bearing plate at the top. The strut assembly may be considered a modified shock absorber and it this strut assembly which needs to be replaced most often. A rubber mount is a part of the strut bearing plate. The rubber mount and the coil spring seldom need to be replaced. However the strut assembly needs replacing frequently. Under present methods when the shock absorber or the strut assembly needs to be replaced the whole MacPherson strut including the strut assembly and the coil spring including the strut bearing plate and rubber mount is removed from the automobile with the spring still in compression. The compression of the spring is between two parts of the strut assembly which are to be replaced. Extreme care and caution then has to be exercised in changing out the strut assembly so as to avoid injury to the mechanic. Typically it takes about one to two hours to replace one MacPherson strut using the conventional method and apparatus depending on the type automobile being serviced.